1. Field of the Invention
This invention relates to a method and apparatus for controlling the temperature within a facility for use in housing animals, and more particularly to a method and apparatus for controlling the operation of a plurality of heating and cooling devices while allowing the status of operation of each such device to be quickly, visually checked by the user.
2. Description of the Related Art
In various industries such as those involving agriculture, it is often necessary to circulate relatively large amounts of air through a building to help maintain the interior of the building within a desired temperature range and to provide adequate ventilation. One such application where ventilation and control of the temperature within a building is extremely important is in connection with poultry houses. Such facilities are typically used to house chickens which are being grown for eventual slaughter or which are being used for egg production. Turkeys are also commonly kept in such poultry houses, although turkeys have been found to be somewhat less sensitive than chickens to large variations in the ambient temperature within the poultry house.
In a large scale poultry house, typically twenty thousand to twenty-five thousand chickens may be housed at a given time. If a poultry house is not properly ventilated, and the ambient temperature within it not properly controlled, the respiration of the chickens and the waste by-products within the poultry house can quickly give rise to a build up of ammonia and heat within the house which may be physiologically detrimental to the chickens. In extreme cases, such as where adequate ventilation and/or cooling is not provided on hot summer days, significant animal mortality may result. Even if mortality does not result, repeated lapses of proper ventilation and/or cooling can produce significant physiological stress on the chickens that result in inhibited growth, reduced egg production, and/or disease. Any of the above conditions may result in significant financial losses to a poultry farmer.
The problem with providing proper ventilation and cooling within a poultry house is exacerbated by the physiological differences between poultry of different ages. For example, very young chickens, hereafter referred to as "chicks", are more tolerant of higher temperatures than older chickens but also more sensitive to lower temperatures. It has been found that chicks suffer abnormal mortality below about 68.degree.-70.degree. F. However, chicks tolerate temperatures into the high 80.degree. F. range quite well. More mature chickens, however, are much more tolerant of lower temperatures but become more susceptible to mortality as the ambient temperature within a poultry house without proper ventilation and cooling, reaches into the 80.degree. F. range. Since chicks and more mature chickens must be housed in the same poultry house, this further increases the criticality of maintaining proper ventilation and a predetermined temperature range within the poultry house.
Further complicating the control of ventilation and temperature within poultry houses is the significant temperature swings experienced during many summer months during various parts of the day. For example, during the summer months the outside temperature is typically warmest between about 2:00 p.m. and 5:00 p.m. In the early evening, such as around 5:00 p.m., any slight wind or breeze present during the day typically dies down. Accordingly, the heat build up within a poultry house without proper cooling can become critically high. Simultaneously, since little or no breeze is present, ventilation within the poultry house, can also become critically poor, leading to an unacceptably high level of ammonia buildup in the building. Within a matter of hours, however, as evening approaches, the ambient temperature may drop significantly. Thus, the need for significant cooling within the poultry house may lessen or be completely eliminated. In this instance, adequate ventilation may be accomplished without the use of power driven cooling implements such as fans. The same situation may arise with the approach of an afternoon thunderstorm. The ambient temperature may drop significantly within a matter of an hour or less while the wind speed of the ambient air may increase significantly.
The above considerations dictate that a plurality of ventilation and cooling devices be carefully controlled to assure proper ventilation and relatively close control over the ambient temperature within a poultry house. Typically, this necessitates the use of one or more passive or active power driven cooling devices used in various combinations to achieve the desired level of ventilation and temperature control. Such devices typically may include power-driven curtains for opening portions of the poultry house to allow natural cross ventilation through the poultry house, a plurality of minimum ventilation fans disposed centrally throughout the poultry house for providing at least a minimum degree of air movement within the house, and/or a plurality of exhaust fans disposed about various walls of the poultry house for drawing air into and through the poultry house. More recently, a plurality of fans for inducing a significant air flow through the entire length of the poultry house to produce a "wind chill"--like effect has been practiced. This has been termed "tunnel" ventilation and is typically implemented at times of day when maximum cooling is needed.
Additionally, the foregoing devices are frequently used in connection with devices for providing some form of evaporative cooling. Such devices are typically known in the industry as "foggers". These devices provide a very fine water mist which helps in providing a cooling effect on the poultry. Well known cooling pads, which also provide evaporative cooling, are also frequently employed.
Frequently, various combinations of the above devices are required to be used for various lengths of times to achieve proper ventilation and temperature control within a poultry house. Merely as an example, during certain hours of the day, such as in the morning, it may be sufficient to have one or more minimum ventilation fans and/or exhaust fans running. As the day progresses, however, and as the temperature typically increases during the day, it may become necessary to open the curtains partially or completely while making all of the minimum ventilation fans operable. As the ambient temperature continues to increase, an even greater degree of cooling may become necessary. In this event it may become necessary to open the curtains completely while one or more exhaust fans remain on to aid in drawing air through the poultry house to achieve a greater degree of cross-ventilation and cooling. It also may become desirable to turn on one or more evaporative cooling devices to further aid in holding down the temperature within a predetermined, desirable range.
As the temperature continues to increase still further, it may become necessary to employ one or more tunnel ventilation fans to create an even greater rate of air flow through the entire length of the poultry house. This form of ventilation has been found to be quite effective in providing a cooling effect on the poultry sufficient to prevent physiological distress, even when the ambient temperature within the poultry house reaches a level which would quickly cause physiological distress or mortality without such tunnel ventilation. Still further, it may be desirable to supplement the cooling effect provided by the tunnel ventilation fans with operation of one or more of the evaporative cooling devices.
As the evening approaches and during night-time hours, the temperature may drop significantly such that sufficient ventilation may be achieved together with a desired ambient temperature within the poultry house with the power driven curtains closed, or almost completely closed, while only one or more of the minimum ventilation fans are operating.
In view of the above, it should be appreciated that a control system capable of controlling the various devices used to provide ventilation and to cool and heat a poultry house must provide a great deal of flexibility in control over numerous heating and cooling devices to maintain proper ventilation and temperature in spite of rapidly changing outside temperatures and wind conditions. In attempts to accomplish this degree of control, most recently developed control systems have typically employed some type of visual display terminal incorporating a keyboard and a menu system to enable a user to program and check the operational status of a number of independent heating and cooling devices. While such systems have proven somewhat effective in accomplishing control over the numerous cooling devices employed to ventilate and cool poultry houses, such systems have also proven to be quite cumbersome and "user-unfriendly" to operate. Exacerbating this problem is the fact that users of such systems may not have had prior operating experience with complicated video display equipment and menu-driven software, and are therefore often hampered in learning how to use such systems quickly without repeated reference to software operating manuals, hardware manuals, etc.
Perhaps the most significant drawback of temperature control systems which incorporate some form of video display terminal, keyboard and menu-driven software is the inability of such systems to provide a means by which each cooling and heating implement associated with a poultry house can be programmed, re-programmed, or its status checked visually, quickly and easily, without requiring the user to manipulate numerous controls or to proceed through numerous questions of a menu-driven software system before reaching the pertinent device. With such prior developed systems, the user is often forced to step through numerous menus or to enter numerous key strokes at a keyboard before finally reaching the portion of the program relating to the device or devices which he wishes to program or to make a status check on. Such systems become particularly cumbersome to program, and are particularly limited in the status information capable of being provided at a glance, when used with large poultry houses employing a plurality of independently controllable power-driven curtains, minimum ventilation fans, exhaust fans, tunnel fans, evaporative cooling devices and heaters.